I have a Worral Thomson one. It's very good, got it from Argos It's really good, with 3 heat settings, low, high, auto.
You also need to decide how big you want it, there are lots of different sized ones.
Low is what I use frequently, I put all my ingredients in about 9.00am and come in about 6.00pm to a wonerfully smelling meal.
High is like a 11.00am -5.00pm kinda time line, quicker cooking than an all dayer.
Auto, it will (I think) cooks slowly, then a little bit quicker, then slower and maintain a temperature.
Like I say it's a good send in the winter, I bung everything in (I don't brown off in the frying pan first), take kids to school, go to work, come home around 6.00 and it's loverly.
All sorts can be cooked in it.
I shove, chicken, potatoes, carrots, onion, herbs, a little water (isn't essential in my one), done.
here's a great thread with loads of recipes in it.
forums.moneysavingexpert.com/showthread.html?t=4273